Entanglement of degenerate eigenstates superpositions

GIOVENALE, NATALIA; FEDERICO M. PONT; SERRA, PABLO; OSENDA, OMAR

Florianopolis

Workshop; Q-Turn : changing paradigms in quantum science; 2018

The entanglement content of superpositions of pairs of degenerate eigenstates of a bipartite system isconsidered in the case that both eigenstates are also eigenstates of the z component of the total angularmomentum. It is shown that the von Neumann entropy of the state that is obtained tracing out one of the parts ofthe system has a definite convexity (concavity) as a function of the superposition parameter and that its convexity(concavity) can be predicted using a quantity of information that measures the entropy shared by the states atthe extremes of the superposition. Several examples of two-particle systems, whose eigenfunctions and densitymatrices can be obtained exactly, are analyzed thoroughly